Esters of nitrohydroxy compounds



1 the action of aliphatic acids or Patented Apr. 24, 1945 ESTERS FNITROHYDROXY COMPOUNDS Henry B. Haas, West Lafayette, Ind., and Byron M.Vanderbilt, Baton Rouge, La., assignors to Purdue Research Foundation,Lafayette, Ind., a

corporation of Indiana No Drawing. Application March 15, 1943, SerialNo. 479,262

2 Claims.

Our invention relates to new and useful esters of nitrohydroxycompounds. More specifically our invention relates to the estersproduced by the anhydrides thereof on nitroglycols.

The esters of the nitroglycols of our invention may be represented bythe following generic forwherein R and R are either hydrogen or alkyl,and R is an all-ryl group having. from two to three carbon atoms. Asexamples of esters which may be included within the scope of ourinvention, there may be mentioned the aliphatic monocarboxylic esters of2-nitro-2-ethyl-1,3-propanediol, 2-nitro-2-isopropyl-1,3-propanediol,2-nitro'-2-propyl-l,3-propanediol, and'the like. More specifically,these esters may be represented by the following structural formulas:

in which R and R represent hydrogen or an by reacting the correspondingnitroglycol with the desired aliphatic acid or anhydride thereof. Whenthe anhydride is used in carrying out this procedure, it is preferablyadded slowly to the nitroglycol, which contains a small amount of amineral acid catalyst, such as hydrochloric, sulfuric, or phosphoricacids. After the anhydride has been added, the reaction mixture isheated, under reflux, at a temperature of from 80-100 C.,"until thereaction is substantially complete, as may be evidenced by the constantboiling point of the crude mixture. If an acid is employed in thepreparation of the nitroglycol esters of our invention, the sameproceduremay be utilized asdescribed above, with the exception that theentire quantity of said acid may be added at once to the nitroglycol.The product thus obtained may then be separated from the remainingorganic acid by means of distillation under reduced pressure. Themineral acid catalyst, if desired, may be removed from the reactionmixture either by adding a substance such as hydrated lime, which willform an insoluble compound therewith, or said catalyst may besatisfactorily removed by treatment with water. On the other hand, it issometimes desirable to distill the ester directly from the acid mediumsince we have found that on certain occasions attempts to neutralize theacid catalyst or to remove it by washing, have resulted in substantiallylower yields than those which can be obtained by. distilling the esterdirectly from the acid medium. Whether or not the acid catalyst isremoved prior to vacuum distillation from the crude ester is immaterial,however, to the subsequent steps of purification since the distillate Iobtained thereby is washed'with a dilute solution of an alkalinesubstance such as sodium bicarbonate, after which it may again betreated with water to insure the absence of acids or other undesirablematerials therefrom. The esters obtained in this manner are ordinarilysuitable for technical use. However, they may be further purified bysubjecting the same toan additional fractional vacuum distillationtreatment.

As examples of acids which can be utilized in the preparation of theesters of my invention, there may be mentioned propionic acid, butyricacid, isobutyric acid, valeric acid, caproic acid, lauric acid, palmiticacid, stearic acid, and the like. In addition, anhydrides of the acidsof the above-mentioned type may also be employed in the production ofthese new esters, and it is to be understood that said acids andanhydrides function asequivalents in my process. drides applicable to myinvention comprise a wide range of compounds of which the following maybe mentioned by way of illustration: propionic anhydride, butyricanhydride, isobutyric anhydride, valeric anhydride, caproic anhydride,and the like.

The nitroglycols employed in the production of these esters may beprepared in accordance with any procedure known to the art. However, weprefer to employ the method described in United States Patent No.2,139,120 by Henry B. Hass and Byron M. Vanderbilt. According to thisprocedure nitroglycols may be prepared by reacting an aliphatic aldehydewith a primary nitro-paraflin in a molecular ratio of 2 moles oialdehyde to one of nitroparaffin in the presence of an alkaline earthmetal hydroxide, such as calcium hydroxide, at a temperature preferablybetween 25-60 C. The aldehyde is added slowly to the nitroparaflin withconstant agitation, .external cooling being employed, if necessary. Ifdesired,

The an yauxiliary solvents such as methyl or ethyl alcohol may beutilized.

Our invention may be further illustrated by the following specificexamples:

Example I 2 nitro 2 propyl- 1,3-propanediol dibutyrate was prepared byreacting 152 parts by weight of 2-nitro-2-propy1-1,3-propanediol and 0.5part by weight of concentrated sulfuric acid, with 182 parts by weightof butyric acid. After this mixture had been maintained at a temperatureof from 80-90 C., for a period of one hour, the ex cess butyric acid wasremoved therefrom in the form of a constant boiling mixture with thewater, which was produced during the esterification, by means ofdistillation under reduced pressure. A quantity of hydrated lime,equivalent to the sul furic acid present, was then added and the crudeproduct distilled under high vacuum. The resulting distillate was washedwith dilute bicarbonate solution, washed with water until neutral.andagain distilled. The product thus obtained boiling at 160 C. (i-mm.)was'a clear, slightly viscous liquid possessing a pleasant odor.

Example II 2-ethyi-2-nitro1,3-propanediol dibutyrat'e was prepared inaccordance with the procedure described in Example I, and was obtainedin 89% yield. This product, a water-white liquid, boiling at 174 C. (8mm.) was found to be soluble in the common organic solvents, includingpetroleum naphthas.

Example III 2-ethyl-2-nitro-1,3-propanediol diacetate was prepared byslowly adding 650 parts by weight of acetic anhydride to 447 parts byweight of 2-ethyl- 2-nitro-1,3-propanediol containing 1 part by weightof concentrated sulfuric acid. When the entire quantity of theacetic-anhydride had been added, the reaction was found to besubstantially complete. The acetic acid, formed during theesteriflcation, was then removed by subjecting the mixture to vacuumdistillation, after which the residue resulting was washed twice withwater, the

with a weak but characteristic ester-like odor and, in general, arerelatively thermostable compounds; while those synthesized from thehigher fatty acid are ordinarily white wax-like solids soluble inbenzene and petroleum ether. Although the physical properties mentionedin the above examples will be helpful in the identification of suchproducts, we do not desire to be restricted to compounds having theproperties disclosed, since these data were taken from singlepreparations and are therefore not to be interpreted as being strictlyrepresentative. 1

The ester of our invention are useful as organic solvents and have beenfound to possess plasticizing properties when incorporated in certaincellulose derivative compositions. These compounds may also be found tobe useful in the synthesis of numerous organic materials. Additionaluses will be apparent to those skilled in the art.

This is a continuation-in-part of our copending application U. S. SerialNo.'340,244, filed June 13, 1940.

Our invention now having been described, what we claim is: l

1. A nitroglycol ester having the following structural formula:

wherein R and R. are members of the group con sisting of hydrogen andalkyl HENRY B. HASS. BYRON M. VANDERBILT.

